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FeedbackPolyarteritis nodosa (PAN) is a necrotizing vasculitis resulting in aneurysmal formation and organ infarction. It is categorized as a medium-vessel vasculitis (Chapel Hill, 2012).
Quick Answers for Clinicians
Diagnosis
Indications for Testing
Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)
Laboratory Testing
- Nonspecific testing – helpful in excluding other diagnoses or identifying organ dysfunction
- CBC – rule out infection
- Urinalysis (UA) – hematuria, proteinuria, red blood cell casts
- C-reactive protein (CRP) – frequently elevated
- Preferred test to detect inflammatory processes (Choosing Wisely: 20 Things Physicians and Patients Should Question, American Society for Clinical Pathology, 2017)
- If CRP not available, order erythrocyte sedimentation rate (ESR)
- Testing to consider to rule out other diagnoses
- Antineutrophil cystoplasmic antibodies (ANCA) – rarely positive, rule out ANCA-associated vasculitis
- Hepatitis B surface antigen – rule out concomitant chronic hepatitis
- Antinuclear antibodies (ANA) – rule out connective tissue diseases
- Antiglomerular basement membrane antibodies – rule out an antiglomerular basement membrane disease (anti-GBM)
Histology
- Small- and medium-size artery necrotizing vasculitis with absence of glomerulonephritis
- Arterioles, capillaries, and/or venules – most affected
- Immunofluorescence fails to demonstrate complement or immunoglobulin in vessel walls
Imaging Studies
Angiography – microaneurysms and stenoses of medium vessels.
Differential Diagnosis
- Alport syndrome
- Connective tissue diseases
- Anti-GBM disease (Goodpasture syndrome)
- Vasculitis – microscopic polyangiitis
- Infection
- Cryoglobulinemia
- Malignancy
Background
Epidemiology
- Incidence –16-25/million for systemic vasculitis as a group (includes eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis, polyarteritis nodosa, and granulomatosis with polyangiitis)
- Age – peak onset in 50s
- Sex – M:F, equal
Risk Factors
Chronic hepatitis B
Clinical Presentation
- Constitutional – fever, malaise, weight loss, arthralgias
- Cardiovascular – acute coronary syndrome
- Dermatological – vascular purpura, livedo reticularis, lower extremity ulcers, subcutaneous ulcers
- Gastrointestinal – nonspecific abdominal pain, gastrointestinal bleeding, bowel perforation
- Neurological – mononeuropathy multiplex
- Renal – renovascular hypertension, vascular nephropathy
Pediatrics
Epidemiology
- Age – peak is 9-11 years
- Sex – M<F, slight
Clinical Presentation
- Tends to be a more limited disorder than in adults
- Constitutional – fever, malaise, weight loss
- Musculoskeletal – arthritis/arthralgia, myositis, myalgia
- Renal – vascular hypertension, hematuria, proteinuria
- Neurological – peripheral neuropathy
- Gastrointestinal – nonspecific abdominal pain
- Dermatological – livedo reticularis, skin nodules, skin infections
Indications for Testing
Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)
Laboratory Testing
- Nonspecific testing
- CBC – anemia, leukocytosis, thrombocytoses
- C-reactive protein (CRP) – usually elevated
- Preferred test to detect inflammatory processes (Choosing Wisely: 20 Things Physicians and Patients Should Question, American Society for Clinical Pathology, 2017)
- If CRP not available, order erythrocyte sedimentation rate (ESR)
- Urinalysis (UA) – proteinuria, hematuria, red cell casts
- Electrolytes – increases in blood urea nitrogen (BUN)/creatinine not uncommon
- Antineutrophil cystoplastic antibodies (ANCA) – rarely positive
Differential Diagnosis
- Infection
- Vasculitis
- Microscopic polyangiitis
- Kawasaki disease
- IgA vasculitis
- Connective tissue diseases
- Alport syndrome
ARUP Lab Tests
Identify anemia, leukocytosis, and thrombocytoses
Automated Cell Count/Differential
Screen for various metabolic and kidney disorders
Reflectance Spectrophotometry/Microscopy
Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)
Quantitative Immunoturbidimetry
Preferred reflex panel for managing patients with a known diagnosis of vasculitis; may be assistive in evaluating suspected vasculitis
For the workup of suspected vasculitis, the preferred panel is antineutrophil cystoplasmic antibodies (ANCA)-associated vasculitis profile (ANCA/MPO/PR3) with reflex to ANCA titer
Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay
Can be ordered as part of the acute hepatitis panel which includes hepatitis A virus (HAV) IgM, hepatitis B virus (HBV) core antibody IgM, HBV surface antigen (HBsAg), and hepatitis C virus (HCV) antibody; refer to acute hepatitis panel with reflex to HBsAg confirmation
Qualitative Chemiluminescent Immunoassay
Reflex pattern: if results for HBsAg screen are repeatedly reactive with an index value between 1.00 and 50.00, then HBsAg confirmation will be added
Aid in initial diagnosis of connective tissue disease
Detect antibodies against double-stranded DNA (dsDNA), histones, SS-A (Ro), SS-B (La), Smith, Smith/RNP, Scl-70, Jo-1, centromere proteins, and other antigens extracted from the HEp-2 cell nucleus
Results are not disease specific
Lower sensitivity than ANA IFA for systemic autoimmune rheumatic diseases
Qualitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody
Reflex pattern: if ANA are detected by ELISA, then ANA, HEp-2, IgG by IFA will be added
Detect glomerular basement membrane (GBM) antibodies in suspected or established anti-GBM disease
May be useful for monitoring treatment response
Positive result should be confirmed by renal biopsy
Semi-Quantitative Multiplex Bead Assay/Qualitative Indirect Fluorescent Antibody
Panel includes GBM antibody, IgG by multiplex bead assay and IFA
Nonspecific test used to detect inflammation associated with infections, cancers, and autoimmune diseases
Visual Identification
Detect acute or chronic hepatitis B virus (HBV) infection
Chemiluminescent Immunoassay
Panel includes ANCA, IgG; myeloperoxidase antibody; and serine proteinase 3 antibody
Reflex pattern: if screen is positive, titer and MPO/PR3 antibodies testing will be added to aid in antibody determination